Sounds good, I will be watching to see what prices are at.
Greg
BluntForceTrauma Wrote:Barrel button is already ordered with a 1:7 twist. SAAMI spec is 1:7.5 but if, let's say, someone was to do a 12" 6mmARC, you'd want it in 1:7 for maximum bullet stability. A 1:7 won't hurt anything in a 20", either, and will only help at long range. There's no real velocity loss to going tighter.
As far as dies go, I'll look into it, but at the moment I've got a lot of irons in the fire....
A lot similar, the shoulder is 0.030 shorter than the 6 Grendel, plus the 6Arc is saami. Allows for seating longer bullets like 103, 105, etc.
Sizing similarity seems akin to the 260 Rem to 6.5 Creed...
"Down the floor, out the door, Go Brandon Go!!!!!"
I am wondering if the case dimensions changes for the 6mm ARC are not so much for any performance increase but so that a 6ppc round or a 6.5 Grendel round would not chamber (Safety)?
Lemonaid Wrote:I am wondering if the case dimensions changes for the 6mm ARC are not so much for any performance increase but so that a 6ppc round or a 6.5 Grendel round would not chamber (Safety)?
You would have a very hard time getting the bolt to close on a 6.5 grendel in a 6mm bore.
The 6ppc could possible fit but I think it would be short enough that the headspace would be so long it couldn't fire.
A5BLASTER Wrote:You would have a very hard time getting the bolt to close on a 6.5 grendel in a 6mm bore.
The 6ppc could possible fit but I think it would be short enough that the headspace would be so long it couldn't fire.
A5B, as you say it would very hard to load one of those rounds in the 6MM ARC as it was designed that way for safety. Those changes do not of them selves grant any extra performance to the round.
The 6mmARC case is well-thought out. When first announced, I thought it should have been longer at 1.59 rather than 1.49, but now I see the logic.
First, it prevents chambering a Grendel. (The nose could get stuck in a 6mm bore and the rest of the bullet pushed back into the case even if the whole bullet wouldn't fit. Having said that, I HAVE seen photos of a stack of 300 Blackout bullets swaged into a 5.56 barrel they sectioned the barrel and who knows how the shooter managed to do THAT.)
Second, the 6mmARC case is also in keeping with Hornady's latest cartridge-to-chamber theories, which make sense to me and are proven out in the 6.5 Creedmoor, 65PRC, and 300PRC.
:: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets
05-04-2020, 08:56 PM (This post was last modified: 06-12-2020, 11:45 AM by Lemonaid.)
Here is a data comparison between 6mm arc and 6ppc and 6.5 grendel.
6 arc-------------------------------6 ppc--------------------Difference---------------
Case length 1.490---------------1.5032------------------.0132 longer for ppc
Base to neck-1.2558------------1.2205------------------.0353 longer for arc
Base to shoulder 1.207---------1.0748------------------.1322 longer for arc
30 degree shoulder--------------30 degree shoulder---
Shoulder diameter-.4301-------.4299--------------------.0002 bigger for arc
Neck outside diameter .274----.2618--------------------.0122 bigger for arc
Neck length--.2342--------------.2827--------------------.0485 longer for ppc
Max coal 2.260-------------------2.1929 -----------------.0671 longer for arc
Neck base to max oal-1.0042----.9724-------------------.0318 longer for arc
6 arc--------------------------------6.5 grendel--------------Difference------------------
case lenth 1.490-------------------1.520--------------------.030 longer for grendel
Base to neck---1.2558------------1.280--------------------.0242 longer for grendel
base to shoulder 1.207------------1.1456--------------------.0164 longer for arc
30 degree shoulder-----------------30 degree shoulder----
Shoulder diameter-.4301----------.430----------------------.0001 bigger for arc
Neck O.D.---.274------------------.293-----------------------(.243 vs .264 )
neck length--.2342-----------------.235-----------------------.0008 longer for grendel
neck base to max oal-1.0042-----.980-----------------------.0242 longer for arc
The neck base to max oal is a key one, that is a general max bullet length before intruding into the case body.
If someone has case data for the 6mm AR, or other variants it would be great if you could post them here.
BFT, what can you tell us about some of the barrels coming out, some have standard gas tube lengths (mid, rifle, etc) while others are using a rifle+1... for 18" and up. One mfr has a 21" barrel and rifle+1.
Others, like faxon and BA seem to be offering regular gas lengths.
Has anyone been discussing why the differences?
"Down the floor, out the door, Go Brandon Go!!!!!"
grayfox Wrote:BFT, what can you tell us about some of the barrels coming out, some have standard gas tube lengths (mid, rifle, etc) while others are using a rifle+1... for 18" and up. One mfr has a 21" barrel and rifle+1.
Others, like faxon and BA seem to be offering regular gas lengths.
Has anyone been discussing why the differences?
For that reason I wouldnt buy a barrel unless its gas tube is rifle+1 for 18 and a 14.5 barrel had a rifle length gas. So to me it looks as though the 6mmARC needs a longer gas system. So a 12 probably will need mid length or even intermediate? But Im sure John will do his research and come out with something that will work!
grayfox Wrote:BFT, what can you tell us about some of the barrels coming out, some have standard gas tube lengths (mid, rifle, etc) while others are using a rifle+1... for 18" and up. One mfr has a 21" barrel and rifle+1. Others, like faxon and BA seem to be offering regular gas lengths. Has anyone been discussing why the differences?
Apparently, some of these guys have had 8 months to play with it, so we'll see what they do but only gonna follow their lead if it makes sense. Right now, it doesn't.
Why? We've got a huge database of knowledge from all the 6mm Grendel wildcats, and none of them NEEDED any special gas-tube lengths.
So, in order to keep costs in line for the average guy, I fully intend to use standard gas-port positions with standard gas-tube lengths. The only fine-tuning, to my mind, might be to the gas-port diameters, but we'll see.
I'm open to being convinced, but at this point will need to hear some amazingly strong technical arguments to make me bother with proprietary gas tubes and such.
:: 6.5 GRENDEL Deer and Targets :: 6mmARC Targets and Varmints and Deer :: 22 ARC Varmints and Targets
Thats another head scratcher for me. If the double secret probation dod unit has them why would they allow the use of non std tubes lengths. Typically the military likes standardized/interchangeable parts.
Knowing everthing isnt as important as knowing where to find it.
rabiddawg Wrote:Thats another head scratcher for me. If the double secret probation dod unit has them why would they allow the use of non std tubes lengths. Typically the military likes standardized/interchangeable parts.
Up to a certain point, I agree.
However, JSOC can buy pretty much whatever they want, as witnessed by the Hk416s, MP7s, suppressors, wide FOV NODs, Mk48s, and who the heck knows what else that shows up in photos full of redacted faces.
